.login-form {
  width: 300px;
  margin: 100px auto 0;
  padding: 20px;
  box-shadow: 0 0 3px #ddd;
}

.input-group {
  margin-top: 20px;
}

.input-group:first-child {
  margin-top: 0;
}

.input-group input {
  box-sizing: border-box;
  width: 100%;
  padding: 10px 5px;
  border: 1px solid #333;
  outline: none;
}

.input-group button {
  width: 100%;
  background-color: lightseagreen;
}